Fuel dispensing device with vapour extraction

ABSTRACT

The invention relates to a method and device for extracting fuel vapour displaced during the simultaneous operation of at least two fuel-dispensing units using a gas pump device. Each fuel-dispensing unit comprises a vapour extraction conduit in which a control valve is arranged. The different vapour extraction conduits are connected to a single gas pump device. The underpressure to be created by the gas pump device and essential for discharge of the correct quantity of vapour is determined, whereafter the control valves are adjusted such that they each allow through the correct quantity of vapour at the specific underpressure.

[0001] The invention relates to a method for extracting fuel vapourdisplaced during the simultaneous operation of at least twofuel-dispensing units using a gas pump device.

[0002] In accordance with national and international regulations forlimiting environmental pollution, fuel-dispensing devices such as fuelpumps must be provided with a vapour extraction. During filling of thefuel tank of a vehicle the fuel vapour present in this tank is displacedby the fuel carried into the tank. This displaced vapour must bedischarged and fed back to the fuel supply tank of the petrol station.The same amount of fuel is discharged from this supply tank as vapour isdisplaced from the vehicle tank, so that the vapour displaced from thevehicle fuel tank can be readily taken up in the fuel supply tank. Whenthe fuel supply tank is refilled, the displaced vapour is received insimilar manner in the fuel tank of the tank truck, which in turn carriesthis vapour to a fuel depot, where a device is available for processingthis vapour. A closed system is thus obtained wherein little or no fuelvapour enters the environment.

[0003] In the known fuel-dispensing devices a gas pump is present whichextracts the fuel vapour displaced from the vehicle fuel tank and pumpsit to the fuel supply tank of the filling station. Because there is anopen connection between the extraction conduit and the vehicle fuel tankat the position of the filling opening thereof, the extraction flow rateof the fuel vapour must be precisely adjusted to the flow rate of thefuel being pumped by the dispensing unit into the vehicle tank. In orderto achieve this each fuel-dispensing device is provided in the vapourextraction conduit with a gas pump and a control valve. This controlvalve is set such that the correct quantity of vapour is extracted. Thecontrol apparatus comprises for this purpose a memory in which is storedthe characteristic of the relation between the position of the controlvalve and the extracted vapour flow rate.

[0004] Devices are known per se with which fuel can be dispensedsimultaneously with two fuel-dispensing units. There is then usuallyalso a choice between different types of fuel. These devices are usuallydesignated as multi-product dispensers (MPD). In order to obtain a goodextraction of fuel vapours, also when fuel is being dispensedsimultaneously with for instance two fuel-dispensing devices, each unitis provided in the prior art with its own gas pump and control valvewhich is controlled in the above stated manner. The dispensing of fuelon the one “side” then does not influence the extraction on the other“side”. Such a multiple embodiment of the vapour discharge entails arelatively high cost of the fuel-dispensing device.

[0005] The invention has for its object to provide a method forextracting the fuel vapour displaced during the simultaneous operationof at least two fuel units using a gas pump device, which method can beperformed with a fuel-dispensing device which can be manufactured atlower cost;

[0006] This object is achieved according to the invention by applyingthe method according to the invention as characterized in claim 1. Onlyone gas pump device is hereby required, even when fuel is beingdispensed simultaneously from a plurality of fuel-dispensing units.

[0007] When fuel is dispensed simultaneously by a plurality offuel-dispensing units, the pump device will have to transport morevapour. By applying the method according to the invention a specificunderpressure is created by the pump device. The control valve of eachfuel-dispensing unit is adjusted such that the correct quantity ofvapour, corresponding with the quantity of fuel dispensed by therelevant fuel-dispensing unit, is extracted at the specificunderpressure. For this purpose the valve characteristics of eachcontrol valve are determined at the specific underpressure.

[0008] According to a preferred embodiment of the invention the pumpdevice is controlled such that the specific underpressure is created onthe suction side substantially irrespective of the extracted flow rate.The valve characteristic therefore need simply contain only the relationbetween the valve position and the vapour flow rate allowed through atthis specific underpressure. Operation of the control valve is thereforesimple.

[0009] The method according to claim 3 is preferably applied herein. Inorder to create the specific underpressure irrespective of the extractedflow rate, a feedback valve is controlled which is received in afeedback line connected to the suction and discharge side of a gas pumpof the pump device. The control of this feedback valve takes place suchthat an underpressure measured on the suction side of the gas pump isheld constant.

[0010] A suitable further embodiment is characterized in claim 4.Although the control of the control valves is more complicated, aseparate feedback valve with associated control is unnecessary in thisembodiment.

[0011] The invention likewise relates to and provides a device forsimultaneous multiple dispensing of fuel as described in claim 5.

[0012] Further advantages and features of the invention will becomeapparent from the following description with reference to the annexedfigures of several embodiments.

[0013]FIG. 1 shows a schematic representation of a first embodiment.

[0014]FIG. 2 shows a schematic representation of a second embodiment.

[0015]FIG. 3 shows a cross-section through a part of the pump deviceaccording to a third embodiment.

[0016]FIG. 1 shows a first embodiment of the device 1 for simultaneousmultiple dispensing of fuel. The device comprises three doubledispensing units 2. Each double dispensing unit 2 can simultaneouslydispense a particular fuel, in this case for instance petrol with a lowoctane number, petrol with a high octane number and unleaded petrol, bymeans of two dispensing nozzles 3. One of the three dispensing nozzlesavailable is therefore chosen in each case on either side of the doubledispensing unit 2.

[0017] In a manner which is further per se known and therefore notshown, fuel is carried from a fuel supply reservoir 6 to the relevantdispensing nozzle 3, from where it is carried into the fuel tank of avehicle.

[0018] Each fuel nozzle 3 is provided with a vapour conduit 4 whichdebouches close to the outlet opening of nozzle 3. The fuel vapourdisplaced from the fuel tank of the vehicle is extracted via this vapourconduit 4. The vapour conduit can be received in the usual manner in thehose which supplies fuel to the nozzle.

[0019] Vapour conduit 4 comprises a valve 5 which is closed when theassociated fuel nozzle. 5 is not being used.

[0020] Each vapour conduit 4 is connected to a collector line 9 or 10.Each collector line is situated on one side of the device so that duringsimultaneous multiple dispensing of fuel with device 1 both collectorlines 9, 10 are in use for extraction of vapour. A control valve 11, 12is received in each collector line 9 and 10. Together with theiroutlets, the control valves 11, 12 are connected to vapour extractionconduit 7. Accommodated in this vapour extraction conduit is a gas pumpdevice 8 which can draw in gas from the vapour extraction conduit andtransport it to supply reservoir 6.

[0021] Present for each dispensing nozzle in each of the dispensingunits 2 is a sensor which measures the dispensed fuel flow rate. Thesesensors are connected via signal lines 15 to control apparatus 16, andmore particularly to the counter computer 17 thereof. This countercomputer 17 processes the measurement signals in the usual manner suchthat the dispensed quantity of fuel can be shown on connected counters,optionally simultaneously with the cost associated therewith.

[0022] Counter computer 17 is embodied such that it feeds the flow ratesignal for each of the sides of device 1 via signal line 19 to controldevice 18 of control apparatus 16. Via lines 19 these flow rate signalsare fed on the one hand to an AND-port 20 and on the other to aso-called chopper to be further described. Control device 18 furthercomprises two memories. A first memory 22, which includes a valvecharacteristic of valves 11 and 12 to be described further, and a secondmemory 21 which includes a characteristic of gas pump device 8. Thequantity of fuel dispensed on both sides of device 1 is thereforetotalled in AND-port 20. This totalled quantity of fuel is fed to a partof control device 18 comprising memory 21. The pump characteristic heldin this memory concerns the relation between the underpressure on thesuction side of pump 8 and the extracted vapour flow rate. As is known,the underpressure on the suction side of gas pump device 8 will decreaseas more gas must be extracted by the gas pump device. This relationbetween the underpressure and the extracted quantity of vapour, which ischaracteristic for the specific pump 8, is predefined and stored inmemory 21.

[0023] In control device 18 is now determined by means of thecharacteristic in the second memory 21 what the underpressure in conduit7 will be during the extraction of a quantity of vapour equal to thequantity of fuel supplied. This underpressure signal is fed to the firstmemory 22 comprising a characteristic of valves 11 and 12. Thischaracteristic concerns the relation between the valve position, theunderpressure and the vapour flow rate allowed through. Theunderpressure which will be set is determined on the basis of the pumpcharacteristic in the second memory 21 and the vapour flow rate for therelevant dispensing unit is likewise fed to the first memory 22. Thevalve position to be applied at the momentary flow rate and theunderpressure follows from the valve characteristic in memory 22. Acontrol signal for this valve position is fed to the relevant controlvalve 11 or 12 via control line 24.

[0024] Chopper 23 ensures that the flow rates associated with therelevant valves are fed alternatingly to the first memory 22 and thedetermined control signal is fed simultaneously to the relevant controlvalve 11 or 12. This takes place using a suitable alternating frequencysuch that valves 11 and 12 are operated quasi-continuously.

[0025] When the dispensed quantity of fuel changes on one or both sidesof device 1, the position of the two control valves 11, 12 is adjustedby control apparatus 16, so that the correct quantity of vapourcontinues to be discharged for the sides in question. When the fueldispensing is for instance stopped on the side of device 1 in whichcontrol valve 11 is arranged, the quantity of vapour to be extracted islimited to the quantity corresponding with the quantity of fueldispensed on the other side. The underpressure in extraction conduit 7will hereby increase and control valve 12 must be controlled in closingdirection so as to still allow passage of the same flow rate.

[0026]FIG. 2 shows a second embodiment 31 of the device for simultaneousmultiple dispensing of fuel. The device comprises three doubledispensing units 32. Each double dispensing unit 32 can simultaneouslydispense a particular fuel by means of two dispensing nozzles 33.

[0027] Each fuel nozzle 33 is provided with a vapour conduit 34 whichdebouches close to the outlet opening of nozzle 33. The fuel vapourdisplaced from the fuel tank of the vehicle is extracted via this vapourconduit 34 and finally enters fuel supply reservoir 36.

[0028] Vapour conduit 34 comprises a valve 35 which is closed when theassociated fuel nozzle 33 is not being used.

[0029] Each vapour conduit 34 is connected to a collector line 39 or 40.Each collector line is situated on one side of the device so that duringsimultaneous multiple dispensing of fuel using device 31 both thecollector lines 39, 40 are in use for extracting vapour. A control valve41, 42 is arranged in each collector line 39, 40. Together with theiroutlets, the control valves 41, 42 are connected to vapour extractionconduit 37. Vapour extraction conduit 37 is connected to the suctionside of pump device 43. A gas pump 38, a feedback control valve 44 and apressure measuring device, 45 are arranged in this pump device. Gas pump38 can draw in gas from the vapour extraction conduit and transport itto supply tank 36. The pressure measuring device 45 is connected to thesuction side of pump device 43 and measures the underpressure in vapourextraction conduit 37. The feedback control valve 44 is connected to thesuction and discharge side of gas pump 38. Through feedback controlvalve 44 gas can flow back from the discharge side of gas pump 38 to thesuction side.

[0030] Present for each dispensing nozzle in each of the dispensingunits 32 is a sensor which measures the dispensed fuel flow rate. Thesesensors are connected via signal lines 46 to control apparatus 47, andmore particularly to counter computer 48 thereof. This counter computer48 processes the measurement signals in usual manner, and forms thefirst measuring unit.

[0031] The counter computer 48 is embodied such that it feeds the flowrate signal for each of the sides of device 31 via signal line 49 to acontrol device 50 of control apparatus 47. Control device 50 comprises amemory 54 which contains the valve characteristic of valves 41 and 42 atthe determined specific underpressure. This characteristic concerns therelation between the valve position and the vapour flow rate allowedthrough. After processing of this information from memory 54, a controlsignal results for each control valve 41, 42 which determines a positionfor the relevant control valve in accordance with the requiredextraction flow rate. This control signal is fed to the relevant valve41 or 42 via a chopper 52 and control line 53.

[0032] Chopper 52 ensures that the flow rates associated with therelevant valves are fed alternatingly to memory unit 22 and thedetermined control signal is fed simultaneously to valve 41 or 42. Thistakes place using a suitable alternating frequency such that valves 41and 42 are operated quasi-continuously.

[0033] Gas pump 38 has a pump capacity which is sufficient to processthe quantity of vapour for extraction at the total maximal flow rate ofthe fuel-dispensing device. At an underpressure set at 200 mbar the gaspump can for instance extract a quantity of vapour at a combined maximumflow rate of the two fuel nozzles 33 of for instance 2×45 l/min.

[0034] The pressure measuring device 45 measures the underpressure atthe intake of gas pump 38. In control unit 50 this measurement signal iscompared to a reference signal stored in memory 54. The differencesignal is used to control the control valve 44 such that the differencetends toward 0. A fixed underpressure can thus be set at the intake ofgas pump 38 using the choice of reference signal.

[0035] When the underpressure is too high, the position of control valve44 is changed such that the underpressure decreases, and vice versa.

[0036] When the dispensed quantity of fuel changes on one or both sidesof device 31, the position of the relevant valve 41 and/or 42 isadjusted by control apparatus 47, so that for the side in question thecorrect quantity of vapour continues to be discharged. When the fueldispensing is stopped, for instance on the side of device 1 in whichcontrol valve 41 is arranged, the quantity of vapour for extraction islimited to the quantity corresponding to the quantity of fuel dispensedon the other side. In order to maintain the underpressure at thedetermined specific value, the setting of feedback control valve 44 ismodified such that the specific underpressure is reset. The controlvalve 41 is closed. There is no change for control valve 42.

[0037] The pump device can be embodied with a mechanical pressuremeasuring device and control valve instead of with an electronic controlapparatus.

[0038]FIG. 3 shows such a mechanical control apparatus in cross-section.Assembly 61 comprises a two-part housing 62, 63 with a space dividedinto two chambers 64, 65. The chambers are separated by a membrane 66.Chamber 64 is connected to both the suction side 67 and discharge side68 of a gas pump 69. The underpressure created by the gas pump prevailsin this chamber 64. In accordance with this underpressure the membrane66 will make chamber 64 smaller or larger. Membrane 66 is arranged forthis purpose between two spring means 70, 71 arranged on both sides ofmembrane 66 in the two chambers 64 and 65. Spring means 70 comprise aspring 72 arranged between two spring cups 73 and 74. Cup 73 isconnected to membrane 66. Cup 74 engages on an adjusting screw 75 whichprotrudes outward through housing part 63. The adjusting screw 75 can betightened, whereby spring means 70 and 71 are compressed and the restposition of the membrane is changed.

[0039] Using the adjusting screw 75 a pre-determined specific value canbe set for the underpressure in accordance with the function of the pumpdevice as described above.

[0040] Membrane 66 is connected to an end of a lever 76 which is mountedon a protruding arm 77 screwed fixedly into housing part 62. The otherend of the lever is connected to a valve member embodied as slide 78.This slide 78 is placed over a tube stub 79 connected to the dischargeside 68 of gas pump 69. Tube stub 79 is provided with openings 80 whichconnect chamber 64 to the discharge side 68 of gas pump 69. Openings 80and chamber 64 form the feedback conduit. Slide 78 forms the feedbackcontrol valve, which opens the feedback conduit to a greater or lesserdegree by closing the openings 80 to a greater or lesser degree.

[0041] When the underpressure on the suction side becomes too strong,membrane 66 will move to the left as seen in FIG. 3. Via lever 76 theslide 78 is then moved to the right as seen in FIG. 3, whereby theopenings 80 are opened further. More gas will hereby flow from dischargeside 68 of gas pump 69 to the suction side 67, whereby the underpressurebecomes less strong. When an underpressure is too low, the reverseaction occurs, whereby the underpressure is strengthened once again. Asubstantially constant underpressure is thus maintained on the suctionside of gas pump 69, irrespective of the quantity of vapour extracted.

[0042] The advantage of this control apparatus and of the apparatusshown in FIG. 2 is that changes in the capacity of the gas pumpoccurring in the course of time due to for instance wear or fouling arecompensated, since the specific underpressure is nevertheless maintainedby the control apparatus.

[0043] The mechanical embodiment of FIG. 3 moreover has the advantage ofa relatively low cost price.

1. Method for extracting fuel vapour displaced during the simultaneousoperation of at least two fuel-dispensing units using a gas pump device,comprising of providing a vapour extraction conduit for eachfuel-dispensing unit which are each provided with a control valve andare together connected to a suction side of the gas pump device, andfurther comprising of measuring the individual fuel flow rate dispensedby each fuel-dispensing unit, having the pump device create a specificunderpressure on the suction side of the pump device, wherein a vapourflow rate substantially equal to the total of the individual fuel flowrates is pumped away, predetermining a valve characteristic for eachcontrol valve of the relation between the valve position and the vapourflow rate allowed through at least at the specific underpressure,determining on the basis of the valve characteristic for each controlvalve the valve position at the specific underpressure and theindividual fuel flow rate of the fuel-dispensing unit with which therelevant control valve is associated, and adjusting each control valveto the determined valve position.
 2. Method as claimed in claim 1,wherein the pump device is controlled such that the specificunderpressure is created on the suction side substantially irrespectiveof the extracted flow rate.
 3. Method as claimed in claim 2, wherein thepump device comprises a gas pump with a suction and discharge side, afeedback conduit provided with a feedback valve and connected to thesuction and discharge side, and a pressure measuring device connected tothe suction side, and further comprising of measuring the underpressureon the suction side during operation, and adjusting the feedback valvesuch that the specific underpressure is substantially maintained. 4.Method as claimed in claim 1, further comprising of predetermining apump characteristic of the relation between different underpressures onthe suction side and the extracted vapour flow rate, wherein thedetermined valve characteristic comprises the relation between the valveposition, the vapour flow rate allowed through and the differentunderpressures, and wherein for the specific underpressure theunderpressure is taken on the basis of the gas pump characteristic at avapour flow rate equal to the total of the individual fuel flow rates.5. Device for simultaneous multiple dispensing of fuel, comprising anumber of fuel-dispensing units which each comprise a fuel conduit and adispensing nozzle connected to the fuel conduit, wherein a fuel pump isarranged in the fuel conduit, a collector line for displaced vapourconnected to each dispensing nozzle, in each of which lines is receiveda control valve, a pump device which is connected on a suction side tothe collector lines and which can create a specific underpressure on thesuction side, and a control apparatus comprising a first measuring unitfor measuring the fuel flow rates dispensed with each fuel-dispensingunit, a first memory containing a valve characteristic for each valve ofthe relation between the valve position and the vapour flow rate allowedthrough at least at a specific underpressure, and a first control unitwhich on the basis of the valve characteristic for each valve candetermine the valve position at the specific underpressure and theindividual fuel flow rate of the fuel-dispensing unit with which therelevant valve is associated, and can adjust each valve to thisdetermined valve position.
 6. Device as claimed in claim 5,characterized in that the pump device comprises gas pump and wherein thefirst memory contains a valve characteristic for each valve of therelation between a valve position, an underpressure and a vapour flowrate allowed through, and the control apparatus further comprises asecond memory containing a pump characteristic of the relation betweenthe underpressure on the suction side and the extracted vapour flowrate, a second control unit which on the basis of the pumpcharacteristic can determine the underpressure on the suction side ofthe gas pump at a vapour flow rate equal to the total of the individualfuel flow rates.
 7. Device as claimed in claim 5, characterized in thatthe pump device comprises a gas pump, a feedback device connected to thesuction and discharge side of the gas pump and a pressure measuringdevice connected to the suction side of the gas pump.
 8. Device asclaimed in claim 7, characterized in that the feedback device comprisesa feedback conduit and a feedback control valve, and the memory alsocontains a determined specific value for the underpressure, and thecontrol apparatus further comprises a second measuring unit formeasuring the underpressure, a second control unit which can determine asetting for the feedback control valve such that the specificunderpressure can be maintained.
 9. Device as claimed in claim 7,characterized in that the feedback device comprises a feedback conduitand a feedback control valve, and the pressure measuring devicecomprises at least two chambers separated by a membrane, wherein onechamber is connected to the suction side of the gas pump and thefeedback conduit such that the underpressure on the suction side can bedetermined with the position of the membrane, and that the membrane isconnected by means of a lever to the feedback control valve to enableadjustment of the feedback control valve so that the specificunderpressure can be maintained.
 10. Control apparatus evidentlyintended for a device as claimed in claims 5-9.